pbuf.c File Reference
`#include "lwip/opt.h"`
`#include "lwip/pbuf.h"`
`#include "lwip/stats.h"`
`#include "lwip/def.h"`
`#include "lwip/mem.h"`
`#include "lwip/memp.h"`
`#include "lwip/sys.h"`
`#include "lwip/netif.h"`
`#include "lwip/priv/tcp_priv.h"`
`#include <string.h>`
`#include "lwip/tcpip.h"`

## Functions

struct pbuf * | pbuf_alloc (pbuf_layer layer, u16_t length, pbuf_type type)
struct pbuf * | pbuf_alloc_reference (void *payload, u16_t length, pbuf_type type)
struct pbuf * | pbuf_alloced_custom (pbuf_layer l, u16_t length, pbuf_type type, struct pbuf_custom *p, void *payload_mem, u16_t payload_mem_len)
void | pbuf_realloc (struct pbuf *p, u16_t new_len)
u8_t | pbuf_add_header (struct pbuf *p, size_t header_size_increment)
u8_t | pbuf_add_header_force (struct pbuf *p, size_t header_size_increment)
u8_t | pbuf_remove_header (struct pbuf *p, size_t header_size_decrement)
u8_t | pbuf_header (struct pbuf *p, s16_t header_size_increment)
u8_t | pbuf_header_force (struct pbuf *p, s16_t header_size_increment)
struct pbuf * | pbuf_free_header (struct pbuf *q, u16_t size)
u8_t | pbuf_free (struct pbuf *p)
u16_t | pbuf_clen (const struct pbuf *p)
void | pbuf_ref (struct pbuf *p)
void | pbuf_cat (struct pbuf *h, struct pbuf *t)
void | pbuf_chain (struct pbuf *h, struct pbuf *t)
struct pbuf * | pbuf_dechain (struct pbuf *p)
err_t | pbuf_copy (struct pbuf *p_to, const struct pbuf *p_from)
err_t | pbuf_copy_partial_pbuf (struct pbuf *p_to, const struct pbuf *p_from, u16_t copy_len, u16_t offset)
u16_t | pbuf_copy_partial (const struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
void * | pbuf_get_contiguous (const struct pbuf *p, void *buffer, size_t bufsize, u16_t len, u16_t offset)
struct pbuf * | pbuf_skip (struct pbuf *in, u16_t in_offset, u16_t *out_offset)
err_t | pbuf_take (struct pbuf *buf, const void *dataptr, u16_t len)
err_t | pbuf_take_at (struct pbuf *buf, const void *dataptr, u16_t len, u16_t offset)
struct pbuf * | pbuf_coalesce (struct pbuf *p, pbuf_layer layer)
struct pbuf * | pbuf_clone (pbuf_layer layer, pbuf_type type, struct pbuf *p)
u8_t | pbuf_get_at (const struct pbuf *p, u16_t offset)
int | pbuf_try_get_at (const struct pbuf *p, u16_t offset)
void | pbuf_put_at (struct pbuf *p, u16_t offset, u8_t data)
u16_t | pbuf_memcmp (const struct pbuf *p, u16_t offset, const void *s2, u16_t n)
u16_t | pbuf_memfind (const struct pbuf *p, const void *mem, u16_t mem_len, u16_t start_offset)
u16_t | pbuf_strstr (const struct pbuf *p, const char *substr)

## Detailed Description

Packet buffer management

## Function Documentation

## pbuf_add_header()

u8_t pbuf_add_header | ( | struct pbuf * | p,
|  | size_t | header_size_increment
| ) |  |

Adjusts the payload pointer to reveal headers in the payload.

Adjusts the ->payload pointer so that space for a header appears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters

  p | pbuf to change the header size.
  header_size_increment | Number of bytes to increment header size which increases the size of the pbuf. New space is on the front. If header_size_increment is 0, this function does nothing and returns successful.

PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so the call will fail. A check is made that the increase in header size does not move the payload pointer in front of the start of the buffer.

Returns
  non-zero on failure, zero on success.

## pbuf_add_header_force()

u8_t pbuf_add_header_force | ( | struct pbuf * | p,
|  | size_t | header_size_increment
| ) |  |

Same as pbuf_add_header but does not check if 'header_size > 0' is allowed. This is used internally only, to allow PBUF_REF for RX.

## pbuf_clen()

u16_t pbuf_clen | ( | const struct pbuf * | p | ) |

Count number of pbufs in a chain

Parameters

  p | first pbuf of chain

Returns
  the number of pbufs in a chain

## pbuf_dechain()

struct pbuf* pbuf_dechain | ( | struct pbuf * | p | ) |

Dechains the first pbuf from its succeeding pbufs in the chain.

Makes p->tot_len field equal to p->len.

Parameters

  p | pbuf to dechain

Returns
  remainder of the pbuf chain, or NULL if it was de-allocated.

Note
  May not be called on a packet queue.

## pbuf_free_header()

struct pbuf* pbuf_free_header | ( | struct pbuf * | q,
|  | u16_t | size
| ) |  |

Similar to pbuf_header(-size) but de-refs header pbufs for (size >= p->len)

Parameters

  q | pbufs to operate on
  size | The number of bytes to remove from the beginning of the pbuf list. While size >= p->len, pbufs are freed. ATTENTION: this is the opposite direction as pbuf_header, but takes an u16_t not s16_t!

Returns
  the new head pbuf

## pbuf_header()

u8_t pbuf_header | ( | struct pbuf * | p,
|  | s16_t | header_size_increment
| ) |  |

Adjusts the payload pointer to hide or reveal headers in the payload.

Adjusts the ->payload pointer so that space for a header (dis)appears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters

  p | pbuf to change the header size.
  header_size_increment | Number of bytes to increment header size which increases the size of the pbuf. New space is on the front. (Using a negative value decreases the header size.) If header_size_increment is 0, this function does nothing and returns successful.

PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so the call will fail. A check is made that the increase in header size does not move the payload pointer in front of the start of the buffer.

Returns
  non-zero on failure, zero on success.

## pbuf_header_force()

u8_t pbuf_header_force | ( | struct pbuf * | p,
|  | s16_t | header_size_increment
| ) |  |

Same as pbuf_header but does not check if 'header_size > 0' is allowed. This is used internally only, to allow PBUF_REF for RX.

## pbuf_remove_header()

u8_t pbuf_remove_header | ( | struct pbuf * | p,
|  | size_t | header_size_decrement
| ) |  |

Adjusts the payload pointer to hide headers in the payload.

Adjusts the ->payload pointer so that space for a header disappears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters

  p | pbuf to change the header size.
  header_size_decrement | Number of bytes to decrement header size which decreases the size of the pbuf. If header_size_decrement is 0, this function does nothing and returns successful.

Returns
  non-zero on failure, zero on success.

## pbuf_strstr()

u16_t pbuf_strstr | ( | const struct pbuf * | p,
|  | const char * | substr
| ) |  |

Find occurrence of substr with length substr_len in pbuf p, start at offset start_offset WARNING: in contrast to strstr(), this one does not stop at the first \0 in the pbuf/source string!

Parameters

  p | pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as return value 'not found'
  substr | string to search for in p, maximum length is 0xFFFE

Returns
  0xFFFF if substr was not found in p or the index where it was found